Its general, the human auditory organ includes an external ear, a middle ear, an internal ear. Here, a path of enabling the human ear to hear the sound will be anatomically described. First of all, the sound energy that, is conveyed by a cascading transfer process of airborne particles is collected by the external ear at the skull and then the sound gathered through the external ear is passed to the eardrum via the external auditory canal, to thereby vibrate the eardrum. Then, the vibrations are passed to the internal ear through the middle ear. The sound energy that is passed to the internal ear moves the lymph fluid in the inside of a cochlea looking like a snail, and then thousands of tiny hair cells inside the cochlea detect movement of the lymph fluid to then be converted into the electrical energy. The converted electrical energy is transmitted to the brain via the auditory nerve to thus enable the human to detect the sound.
However, in the case that functions of transferring the sound or electrical energy do not smoothly facilitate from the external ear to the auditory nerve as described above, the hearing sense degrades or impaired hearing occurs. Usually, in the case of these patients, the hearing aids are essentially used in order to compensate for the sound by converting the sound into the electrical energy. These hearing aids are devices intended to amplify or vary the sound of the band which can be heard by persons of the normal auditory sense, and thus enable persons of the abnormal auditory sense to perceive the sound in the same manner as those of the persons of the normal auditory sense. However, since the hearing aids are small compact devices enough to wear the hearing aids in or after the ears of wearers during use, the hearing aids should be individually programmed by experts of fitting hearing aids according to prescription in order to amplify the frequency range that is difficult for a user to recognize it before use of the hearing aids.
Here, Korean Patent Laid-open Publication No. 10-2001-0008008 whose title is “Method of automatically fitting hearing aids” published on Feb. 5, 2001 is one of the prior art applications filed by the applicant Sim Yunju.
Then, a conventional hearing aid having the same structure as described above will be described with reference to FIG. 1. In FIG. 1, the conventional hearing aid includes: a microphone 71 that converts a sound which is collected by a bodily ear 70 into an electrical signal and that outputs the electrical signal; an amplifier 72 that amplifies the sound signal output from the microphone 71 into a certain level; a receiver 73 that outputs the sound signal output from the amplifier 72 into a vibration signal that can be heard by the human body, a case member 74 including the microphone 71 having the receiver 73, and the built-in amplifier 72; and a switch unit 75 that is connected to one of the amplifier 72 to thus adjust a recognition frequency manually.
In addition, a battery 76 that supplies power to internal circuitry including the amplifier 72 is housed in the case member 74.
The operation of the above-mentioned conventional hearing aid will be described below. First, the hearing aid 77 will be fitted individually by an expert of fitting hearing aids according to prescription in order to amplify the frequency range that is difficult for a user to recognize it before wearing the hearing aid in the bodily ear. After the hearing aid 77 fitted as described above is worn in the ear of the human body and then the human voice occurs outside, the human voice is collected through the microphone 71 to then enter the amplifier 72. Then, the amplifier 72 amplifies the input human voice signal into a frequency level set by the switch unit 75 to then be output to the receiver 73. Thus, the receiver 73 converts the sound signal output from the amplifier 72 into a vibration signal detected by the human ear to then be emitted into the ear of the human body and to thereby perform the normal function of the hearing aid.
However, in the case that an amplification level fitted by an expert is changed by a multiplicity of causes in the conventional hearing aid, the wearer should directly adjust the amplification level according to his or her hearing ability. In this case, when the wearer takes out the hearing aid from the ear and manipulates the switch unit with wearer's fingers, it is very difficult to manipulate the switch unit with wearer's fingers in most cases, to thereby cause it very difficult to manipulate the hearing aid and significantly decrease convenience of users of the hearing aid.